1. Field of the Invention
The present invention relates to a process and an apparatus for producing underlying stitch sewing data.
2. Related Art Statement
Underlying stitch sewing is carried out on a work cloth for forming underlying stitches inside an embroidery area, before the embroidery area is filled with embroidery stitches to produce an embroidery, so that the embroidery stitches formed over the underlying stitches can be seen to have an appropriate swell or three-dimensional effect. In addition, the underlying stitches serve for preventing the work cloth from shrinking, as the embroidery stitches are formed in succession in the embroidery area.
The Assignee of the present application disclosed, in Japanese Patent Application laid open under Publication No. 3-289989 on Dec. 19, 1991, the technique of automatically producing underlying stitch sewing data for forming, in each of quadrangular blocks connected to each other in an array, unit underlying stitches which alternately connect between two sides of the quadrangle which are opposed in a direction generally perpendicular to an embroidering direction in which embroidery stitches are formed in succession in an embroidery area. According to the underlying stitch sewing data, the underlying stitches are formed from one of the remaining two opposed sides of each quadrangular block, toward the other side thereof, in an underlying stitch sewing direction generally parallel to the embroidering direction, with a predetermined stitch density (e.g., number of unit underlying stitch or stitches formed in a unit length as measured in the underlying stitch sewing direction). A unit underlying stitch may consist of a single stitch or a plurality of stitches formed along a straight line segment connecting between the opposed sides. Furthermore, according to the underlying stitch sewing data, the underlying stitches are formed from the first block of the array of blocks to the last block of the same.
Thus, the above-indicated technique enables automatic production of underlying stitch sewing data with high efficiency. However, the automatic production of underlying stitch sewing data is effected by using a pre-stored set of underlying stitch area outline data representative of an outline of an underlying stitch area. Thus, this technique does not provide for automatically producing underlying stitch area outline data by using embroidery area outline data representative of an outline of an embroidery area to be filled with embroidery stitches.